Azo pigments



AZO PIGMEN TS No Drawing. Application February 15, 1957 Serial No. 640,340

Claims priority, application Switzerland March 2, 1956 7 Claims. (Cl. 260-176) The present invention concerns greenish to reddish yellow pigments of the azo series which are distinguished by their good fastness to light and their ability of practically not migrating in lacquers or thermoplastic synthetic substances. The invention also concerns the production of these new azo pigments, the use thereof for pigmenting natural and synthetic high molecular substances and, finally, as industrial product, the materials fast coloured with the aid of the pigments according to the present invention.

It has been found that azo pigments having very good fastness to light and migration are obtained if compounds of the general Formula I wherein X represents a linear bridging member embracing two carbon atoms in Which the carbon atoms are saturated by oxygen, hydroxyl groups and/ or hydrogen, are tetrazotised and coupled with such azo components as contain a ketomethylene group which can be coupled and contain no acid water solubilising groups. Thus the linear bridging member X of the tetrazonium component consists of two identical or different members of the series of the carbonyl, hydroxymethylene and methylene groups. The amino compounds used for the production of the diazo components according to the present invention can be produced by methods known per se from known starting products. Thus, from the already known 4.4-dichlorobenzil, 4.4'-dichloro-3.3-dinitrobenzil is obtained by nitration. From this compound 4.4-dichloro-3.3'- diaminobenzil is obtained under suitable reduction conditions. 4.4dichloro-3.3'-diaminobenzoin and -hydrobenzoin can be prepared from this compound or direct from 4.4'-dichloro-3.3-dinitrobenzil by catalytic hydrogenation. Also mixtures of amino compounds which correspond to the general Formula I can be used, for example technical mixtures of compounds obtained in the Various stages of reduction such as occur under certain conditions in the hydrogenation of 4.4-dichloro-3.3' dinitrobenzil. The last step of the reaction to form 4.4'-dichloro-3.3'-diaminodibenzyl can be performed advantageously with hydrazine. However, also other methods known per se can be used to produce 4.4-dichloro-3.3'-diaminobenzil and compounds which are derived therefrom by reduction or hydrogenation of the diketo group.

The simplest way of tetrazotising these diamino compounds is, for example, in mineral acid medium in the cold with sodium nitrite.

As azo components having a ketomethylene group which can be coupled, both those containing the group in open chain as well as those in which it forms a component of a heterocyclic ring can be used according to the present invention. The azo components should not conatenlt tain any acid water solubilising groups such as the sulphonic acid and the carboxyl group. Examples from the class of acyl acetic acid derivatives containing the ketomethylene group in open chain are acetoacetic acid anilide, acetoacetic acid chloranilides, dichloranilides,

toluidides, chlorotoluidides, xylidides, anisidides, phenetidides; acetoacetic acid dimethoxy cyananilide, 2.5-dimethoxy-4-chloranilide; benzoyl acetic acid anilide and di-acetoacetic acid-o-tolidide. Examples of compounds containing the ketomethylene group in. a heterocyclic ring are 5-pyrazolone derivatives such as l-phenyl-3- methyl 5 pyrazolone, 1-phenyl-3-carbethoxy-5-pyrazolone, the three l-(chlorophenyl)-3-methyl-5-pyrazolones, tolylmethyl-S-pyrazolones and also e. g. dihydroxyquinolines.

The diazonium compounds according to the present invention are coupled with the azo components by methods known per se.

If desired, capillary active compounds such as wetting agents, dispersing agents and/ or protective substances can be added either during or after the production of the pigments. For example solutions of alkali soaps of higher fatty acids, colophony soaps or also emulsions of fats, parafiins, waxes or fatty oils and also plasticisers such as are used in the lacquer and plastics industry and which can be produced with the aid of soap or other emulsifiers are suitable for this purpose. It is possible to obtain pigments of a softer texture by the addition of such auxiliary agents. If desired, the pigments can also be produced in the presence of other organic or also inorganic substrata. After isolation, the pigments are converted, if necessary with the addition of organic or also inorganic binding and/ or diluting agents, into the form desired for use, e. g. in the form of powders, pastes, semi-solid or solid concentrates (masterbatches). The so-called flushing process is advantageous for the preparation of pastes in organic agents.

The azo pigments claimed have the general formula:

wherein X represents a bridge selected from the group consisting of A represents a member selected from the group consisting of 1-phenyl-3-methyl-5-pyrazolon-4-yl and a-actoacetic acid phenylamide radicals.

Because of their pure greenish yellow shade, the compounds which contain an acetoactic acid derivative as azo component are particularly valuable. They correspond to the formula:

wherein X is a bivalent bridging member as defined above, and B represents a mononuclear carbocyclic aryl radical.

The azo compounds according to the present invention are particularly suitable for pigmenting high molecular natural and synthetic substances such as rubber, paints and lacquers, organic polymerisation, polycondensation and polyaddition products. They are also suitable for the pigmenting of spinning masses for synthetic fibres, in particular for viscose and for pigment printing on textiles.

The greenish to reddish yellow pigmentations and prints obtained are distinguished by their remarkable fastness to light, their transparency and their good fastness to oil and cross lacquering. Some of them are also distinguished by their purity of shade. In thermoplastic synthetic substances, e. g. in polyvinyl chloride, the pigments according to the present invention have no, or only a slight, tendency to migrate. They are excellently fast to heat and cross lacquering in so-called stoving lacquers.

The following examples illustrate the invention without limiting it in any way. Where not otherwise stated, parts are given as parts by weight and the temperatures are in degrees centigrade. The relationship of parts by weight to parts by volume is as that of kilogrammes to litres.

Example 1 15.45 parts of 4.4'-dichloro-3.3-diaminobenzil are heated for a short time in 75 parts by volume of N-hydrochloric acid, then cooled and 250 parts of ice water are added. The whole is then tetrazotised at 5-10" with 100 parts by volume of l N-sodium nitrite solution.

18.4 parts of acetoacetic acid anilide are dissolved in 900 parts of water of 65 and 12 parts by volume of Elementary analysis:

calculated for found 4.4-dichloro-3.3-

dinitrobenzil CmHsOBNzClg Percent Percent A suspension with a particle size of about 1 to 5 is produced by grinding 184.5 parts of 4.4-dichloro-3.3- dinitrobenzil with 5 parts of a non-ionogenic dispersing agent of the ethylene oxide type and water. This paste is poured into a 95 warm suspension of 250 parts of cast iron filings in 300 parts of water and 10 parts by volume of hydrochloric acid conc. The paste should be in an iron vessel and is stirred for 5 /2 hours at The reaction is then made weakly alkaline with sodium carbonate, the reaction mixture is cooled, filtered and the product is washed and dried. By repeated extraction with hot ethyl acetate and evaporation, the dia'mine is obtained in the form of intensive reddish yellow crystals with melt at 193-195 (corr.). Content, according to nitrite used: 96.4%.

Elementary analysis:

10 N-hydrochloric acid. 110 parts of crystallised sodium calculated i61- acetate dissolved in 330 parts of Water and 1.5 parts of found agigt gg g-g" triethanolamine oleate emulsified in 60 parts of Water o n mmo are added. 0.4 part of decolourising carbon is then added to the tetrazo solution which is then poured in one Percent Percent hour through a filter while stirring into the 810 cold 54-66 54-40 3.11 3.26 acetoacetic acid amhde suspension. After stirring for 2 8.95 9.06 hours at 20, the product is filtered off, washed and 2250 22-95 dried at 60. It corresponds to the formula CHa-CO I CO-GHa /CN=N 1 1=N-o Q- From the pigment so obtained for example, very pure, Example 2 greenish yellow polyvinyl chloride sheets of high transparency and very good fastness to light can be produced. The sheets are practically fast to migration.

If in this example, 18.4 parts of acetoacetic acid anilide are replaced by 19.7 parts of acetoacetic acid-ptoluidide and 1500 parts of water of 80 are used as well as hydrochloric acid to dissolve, then a more strongly coloured yellow which is somewhat more reddish is obtained. It has similar fastness properties.

The 4.4-dichloro-3.3-diaminobenzil used in this example is produced as follows:

279 parts of pulverised 4.4-dichlorobenzil are slowly A tetrazo solution is prepared according to Example 1. Also 21.8 parts of acetoacetic acid-p-chloranilide are dissolved in 900 parts of water and 360 parts of 2 N-caustic soda lye. At 8 to 10 glacial acetic acid is added dropwise while stirring until the reaction is neutral to litmus paper and then an emulsion of 1.4 parts of triethanolamine oleate in 56 parts of water is added dropwise. The filtered tetrazo solution is then added in one hour while stirring. On completion of the coupling,-themixture is filtered, the product washed and dried at 60. It corresponds to the formula added while stirring into 500 parts by volume of turning nitric acid, the temperature not being allowed to exceed 60. The whole is then stirred for 6 hours at 63-67 cooled and the reaction mixture is poured into 2700 parts of ice water. The yellow precipitate is filtered off under suction, washed with ice water and alcohol and dried. Yield: 324 parts, M. P. 195l97 (corr.) content, determined titanometrically: 98.8%.

A greenish yellow pigment which has very good fastness to light inpolyvinyl chloride is obtained. It has only a very slight tendency to migrate.

Analogous pigments can be produced from acetoacetic acid-o-anisidide, -p-anisidide, -2.5-dimethoxy-4-chloranilide or -m-xylidide. They have greenish to reddish yellow shades and have very good fastness properties in polyvinyl chloride.

2,858,303 a 5 6 Example 3 Example 4 15.65 parts of 4.4-di h1o1-0-3,3'-di i h d b i A tetrazo solution trom 4.4-dichloro3.3'-diaminobenin 400 parts of water and l25 parts by volume of 2 zil is prepared according to Example 1. Also 18.0 parts N-acid are tetrazotised at -3 with 100 parts by volume of Phenyl methyl Pyrazolone are dlssolved m 1500 P of l N-nitrite solution. In addition, 18.25 parts of aceof Water and 60 Parts by Volume of 2 N'hydmchlonc acid, the solution is cooled to 0 to 3, and 360 parts by 2???? 3 3 22 fi g 23 1 3 i if volume of 2 N-sodium acetate solution are added dropn 0 p y o u 0 Wise while stirring in half an hour and then the filtered N'hydrochlonc acld' .After the addition of 160 parts tetrazo solution isadded dropwise in another half hour. by volume of 2 N-sodium acetate solution and 1.6 parts 0 on completion of th coupling, the product is filtered of triethanolamine oleate emulsified in a little water, the Off, Washed and dried. The reddish yellow pigment has Volume is brought P to 2000 Parts y Volume and the very good fastness to heat and light and fairly good fasttemperature to 8-10 and the clear tetrazo solution is ness to migration. It corresponds to the formula CH: CHI

poured in while stirring in one hour. The temperature is A strong reddish yellow pigment which has very good then raised to 20. On completion of the coupling, the fastness to light and cross lacquering is obtained in an whole is heated for another hour at 85-90, the product 3 manner from is filtered off, washed and dried at 60. A brilliant, drobnzom and PhenY1methY1PYraZ1negreenish yellow pigment is obtained which has excellent If m the above examp 1-(2 'chloropheny1) 3'methyl 5-pyrazolone is used instead of 1-phenyl3-rnethyl-5-pyrazfastness to heat and cross lacquering 1n stoving lacquers Clone, or if 1 (4' methy1pheny1) 3 methyl s pyrazolone and which has good fastlless t0 light The Pigment is used, then similar pigments having similar properties responds to the formula i are obtained.

on 0 OZ E Q 0 on B 0 3 H H CH-N=I1T l V=N-C A similarly valuable product is obtained if in this Example 5 example the acetoacetic acid anilide is replaced by 19.7 3 parts f 4,4'.dich10ro-3 3zdiaminodibenzyl are parts of acetoacetic acid-p-toluidide. dissolved in 25 parts by volume of 2 N-hydrochloric acid The 4.4'-dich1oro- 3 3-diamino-h d benz i used i and 80 parts of water and the solution is tetrazotised hi example is'produced as follows; at 03 with 20 parts by volume of 1 N-nitrite solution. 92.3 parts of 4.4'-dichloro-3.3-dinitrobenzil, produced 40 Also parts of acetoacetlc allude are d lsolved m as described in Example 1, is treated at 50 to 60 in 1000 300 parts by volume of Water Wlth the addmon of 12 i i i i arts by volume of 2 N-hydrochloric acid. 32 parts by P t by Volume of ethanol Wlth the addltlon of 13 Parts olume of 2 N-sodium acetate solution are added and of a Platinised charcoal catalyst, with y g at low the whole is cooled to 04. The filtered tetrazo solu- "P duratiolli 2 y y g taken p 45,600 tion is then added dropwise while stirring to the above parts by volume. The reaction mass is filtered and the olution, the addition being performed within half an residue is extracted at 70 with 1 N-hydrochloric acid. hour on completionoof the p g the whole i The filtrate is then made weakly alkaline to litmus heated for one 11uat85 The l then filterefl paper with sodium carbonate solution and the precipi- .washed dned A very pure yellow is tated white base is isolated and dried M P 231 236 obtained which has good fastness to light. and does not mi ate in 01 in l chloride. The i ment corresponds (corn); yield according to mtrlte used: 95.7%. p to f g lg y P g Elementary analysis? If in the above example the 3.65 parts of acetoacetic calculated for anilide are replaced by 3.95 parts of acetoacetico-anisidide, a pigment having slmllar properties 1s obtained. found 3.3-diamino- The 4.4'-d1chloro-3.3'-d1am1nod1benzyl used is progi fggj gfg duced as follows: A mixture of 9.3 parts of 4.4'-dichloro- 3.3-diaminobenzil, 110 parts of diethylene glycol, 6.2 Percent percent parts of hydrazine hydrate and 8 parts of potassium by- C 2-2? 2' S droxide is slowly heated to 200 11]. a round flask fitted I- 9: 10 s: 95 with an ascending tube and then the temperature is kept G1 40 62 at 200 for 3 hours. After cooling, the solution is poured A base with similar analysis values isobtained if 77.2 into @QP of Water and the product which precipiparts f 4 4' di h1 3 3Ldi i b fl are hydrogem tates is isolated. It 1s purified by dissolvlng in diluted ated in an analogous manner but with about a quarter of hydrochloric acid, PreQiPitating With Sodium Carbonate the amount of hydrogen mentioned above. In the infra- Solution and then reclystallising from hydrous FY red spectrum it was found that the 0:0 b d t 598, i i and from alcohol with the addition of decolourising carin 4.4-dichloro-3.3'-diaminobenzil was missing in the hon. An almost white base is obtained which melts at hydrogenated product. 161-164 (corn).

wherein X represents a bridge selected from the group consisting of Elementary analysis:

CHTOHP, -cH-onand -o o calculated for I I ll found 4. i'-d ichlqro-3.3- H 0H 0 O dlammodlbenzyl A represents a member selected from the group consist- C14H14N2C12 s U I mg of 1-phenyl-3-methyl-5-pyrazolone-4-yl and a-aceto- Pmmt Percent acetic acid phenylamide radicals.

52. 5 5 52.3 2. An azo pigment havmg the general formula:

9198 9195 24.61 25.3 10 O G 0 O I ll Hac( 3 111' I l 0-011; What we claim is: L- 1. An azo pigment having the general formula:

B-HN-G6 CONHB wherein X represents a bridge selected from the group consisting of --CHr-CHz-, GH-OH- and --00 H OH B represents a mononuclear carbocyclic aryl radical.

3. An azo pigment having the formula:

QOXQQ 0 HaG- 5. An azo pigment having the formula:

7. An azo pigment having the formula:

mc-Onn-co 0 o-NH-O-on.

References Cited in the file of this patent UNITED STATES PATENTS Ulrich Feb. 14, 1899 Murphy Feb. 27, 1940 OTHER REFERENCES D. W. Hein et al.:JACS, 1955, vol. 77, pp. 4107-4110, New Pigments From 3,3'-Dichloroand 33'-Dimethoxy- 4,4'-Dia minostilbene. 

1. AN AZO PIGMENT HAVING THE GENEFAL FORMULA: 